Basel-based pharmaceuticals company Naari has issued an impassioned plea to the US state of Nebraska to return drugs that could be used to kill prisoners on death row.

"Naari did not supply these medicines directly to the Nebraska Department of Correctional Services and is deeply opposed to the use of the medications in executions," CEO Prithi Kochhar wrote in a letter addressed to Nebraska Supreme Court Chief Justice Michael Heavican. He also sent the letter to Nebraska Attorney General Jon Bruning, the Journal Star newspaper reported.